The use of adhesives and sealants in the automotive industry is becoming increasingly important. Adhesives and sealants are used in the assemblies of such hem-flanged parts as doors, decks, beds and hoods. For example, sealing materials can be used in conjuction with more conventional spot-welding techniques. The sealant is first applied and then the sheet metal is welded through the sealant. Such a combined approach has allowed the distance between spot welds to be increased while reducing the number of welds. Some manufacturers, moreover, have eliminated the welding altogether by employing structural adhesives.
The application of sealant material to the seam or intersection of surfaces in an assembly line operation is presently a manual task requiring operator adjustment to vehicle position and seam location. The manual application of adhesives and sealants to assemblies has been found to be generally impractical because of the high throughput and high accuracy required. The present automotive manufacturing environment places exacting demands on systems that can automatically apply adhesives and sealants. Adhesives and sealants must be applied accurately, along the right bead path, in the required cycle time, in the precise volume required, and with the proper cross section. Otherwise, incorrect bonding or squeezing or bead placement will occur.
While numerous automation techniques have been employed in various assembly line operations, the randomness of the position of a vehicle on the assembly line, coupled with the imprecise tolerances of vehicle surfaces defining a seam have discouraged economical automation of the process of applying sealant to such seams.
Commercially available seam tracking systems employing two dimensional sensing arrays and extensive data computing capability have proven to be too costly and complex for automating the sealant dispensing process.
It is therefore an object of this invention to provide a simple, inexpensive two-dimensional seam locating and tracking appartus which will reliably locate and track a seam.